<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<!-- 
See javadoc API for class org.thymeleaf.expression.Sets

转换为Set
${#sets.toSet(object)}
计算长度
${#sets.size(set)}
检查set是否为空
${#sets.isEmpty(set)}
检查元素是否包含在set中
${#sets.contains(set, element)}
${#sets.containsAll(set, elements)}
 -->
<p th:text="${#sets.size(set)} "></p>
<p th:text="${#sets.isEmpty(set)} "></p>
<p th:text="${#sets.contains(set, 1)}"></p>
<p th:text="${#sets.containsAll(set, elements)}"></p>
</body>
</html>